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Ontario · climate station 6131415 · 180.0 m

Chatham Wpcp

Average last spring frostApril 24
Average first fall frostOctober 26
Frost-free period185 days

1981–2010 normals; ECCC quality code “D” (A = WMO “3 and 5 rule”; B ≥ 25 years; C ≥ 20 years; D ≥ 15 years of data). An average is not a guarantee: a late frost is still possible.

Probabilities

10%25%33%50%66%75%90%
Spring frost (0 °C or lower) on or afterMay 3April 29April 27April 24April 20April 18April 12
Fall frost on or beforeOctober 8October 13October 19October 29November 3November 5November 11
Frost-free period ≤ (days)160173178186192196204

Example: the spring 10% column is the date after which a frost occurs in only one year in ten.

Indicative planting calendar

Start tomatoes, peppers and eggplant indoorsFebruary 27 – March 13
Sow peas, spinach, lettuce and radish outdoors (frost-tolerant)March 27 – April 10
Plant potatoes and onion setsApril 10 – April 24
Transplant tomatoes and peppers; sow beans, corn, squash and cucumbersMay 1 – May 15
Last sowing of quick crops (radish, lettuce, spinach)September 11 – September 26
Harvest or cover frost-tender cropsOctober 19 – October 26
Plant garlic and spring bulbsOctober 26 – November 23

General gardening rules of thumb computed from this station's average last/first frost dates; they are not ECCC data. Adjust to local conditions and seed-packet instructions.

Nearby stations

Sarnia Airport · 172 dNew Glasgow · 163 dWindsor A · 195 dSt Thomas Wpcp · 152 dIlderton Bear Creek · 160 dLondon Int'l Airport · 164 d
Sources & licences

Environment and Climate Change Canada — Canadian Climate Normals 1981–2010 (station data, MSC Datamart) (30-year averages; not updated). Retrieved 2026-10-18 19:10 UTC.
Data Source: Environment and Climate Change Canada Environment and Climate Change Canada Data Servers End-use Licence.

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